Facet joint injection: a rare form cause of epidural abscess formation.

The posterior zygo-apophyseal joints (facet joints) may be a significant source of back pain. Invasive treatment typically consists of injecting the joints with local anaesthetic and steroid or by radiofrequency ablation of the nerve supply to the joint. Facet joint injection is generally considered to be a very safe procedure with few significant side effects reported. Epidural abscess is a rare but potentially very serious occurrence. Most cases occur spontaneously but the condition may complicate epidural anaesthesia, spinal anaesthesia or epidural steroid injection. We report a case in which facet joint injections resulted in epidural abscess formation. To our knowledge this has not previously been reported.